Heat sink assembly

ABSTRACT

A heat sink assembly includes a heat exchanging section formed by a thermally conductive sheet folded into alternating ridges and troughs defining generally parallel spaced fins having opposite end edges. The folded sheet is formed into a generally cylindrical configuration whereby the troughs form an inner-segmented cylinder and the ridges form an outer-segmented cylinder generally concentric with the inner cylinder. The heat sink assembly may include a heat conductive rod dimensioned to engage the troughs of the thermally conductive sheet. The ridges of the thermally conductive sheet may also contain apertures to allow air to fully circulate through the fins. The heat sink assembly may also include a fan and a thermally conductive base plate.

[0001] This application is a continuation of application Ser. No.09/386,103, filed on Aug. 30, 1999.

FIELD OF THE INVENTION

[0002] This invention generally relates to cooling devices such as heatexchangers and, particularly, to a heat sink assembly having an improvedheat exchanger arrangement.

BACKGROUND OF THE INVENTION

[0003] In various industries, such as in the computer industry, there isa need for low cost high performance heat exchangers to cool suchcomponents as microprocessors or semiconductors. Many semiconductorscreate so much heat that they can be irreparably damaged if the heat isnot removed. Consequently, heat exchangers employing heat sinks havebeen used to pull the heat away from the semiconductor and disperse thatheat into the atmosphere. The present invention is directed toimprovements in such heat sink assemblies.

SUMMARY OF THE INVENTION

[0004] An object, therefore, of the invention is to provide a new andimproved heat sink assembly of the character described.

[0005] In one embodiment of the invention, the heat sink assembly usedto dissipate heat from a heat producing electronic device includes aheat exchanging section having a thermally conductive sheet folded intoalternating ridges and troughs defining generally parallel spaced finshaving opposite end edges. The folded sheet is formed into a generallycylindrical configuration, whereby the troughs form an inner-segmentedcylinder and the ridges form an outer-segmented cylinder generallyconcentric with the inner cylinder. The heat exchanging section is inthermal contact with a heat-producing device via a thermally conductivepath which is thermally connected to at least one of the troughs of thefins.

[0006] The invention contemplates that the assembly may include acylindrical heat conductive rod within the inner-segmented cylinderdefined by the troughs of the folded sheet. The rod is dimensioned forengaging the troughs, and the fins are generally parallel to the rod.The rod may be hollow, solid or comprise a fluid filled heat pipe.

[0007] The heat sink assembly is shown as part of a heat exchangerassembly including a fan mounted on the heat exchanging section at anend thereof opposite the heat producing electronic device. The end edgesof the fins adjacent the heat producing electronic device are spacedfrom the heat producing electronic device so that the fan can circulatecooling air completely through the heat exchanging section.Alternatively, in situations where the overall length of the heat sinkassembly is a design driver, apertures can be place in the ridges of thefins so that the end edges of the fins can be placed on the heatproducing electronic device, with the apertures in the ridges of thefins allowing air to circulate fully through the heat exchangingsection.

[0008] The invention may also have a thermally conductive base plate atan end opposite the fan.

[0009] Other objects, features and advantages of the invention will beapparent from the following detailed description taken in connectionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The features of this invention which are believed to be novel areset forth with particularity in the appended claims. The invention,together with its objects and the advantages thereof, may be bestunderstood by reference to the following description taken inconjunction with the accompanying drawings, in which like referencenumerals identify like elements in the figures and in which:

[0011]FIG. 1 is a top perspective view of a heat exchanger assemblyincorporating the heat sink assembly of the invention;

[0012]FIG. 2 is an exploded perspective view of the heat exchangerassembly of FIG. 1; and

[0013]FIG. 3 is an exploded perspective view of the heat exchangerassembly of FIG. 1 including a base plate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Referring to the drawings in greater detail, one embodiment ofthe invention is incorporated in a heat sink assembly, generallydesignated 10, which includes a circular fan assembly 12 having leadwires 14 extending therefrom and terminating in an electrical connector16. The fan assembly is mounted on top of a heat exchanging section,generally designated 18. The heat exchanging section, in turn, ismounted above a base assembly, generally designated 20.

[0015] More particularly, heat exchanging section 18 includes athermally conductive sheet, generally designated 22, which is foldedinto alternating ridges 24 and troughs 26 defining generally parallelspaced fins 28 having opposite end edges 30 and 32. Folded sheet 22 isformed into a generally cylindrical configuration as best seen in FIG.2, whereby troughs 26 form an inner segmented cylinder 34 and ridges 24form an outer segmented cylinder 36 generally concentric with innercylinder 34. The inner and outer cylinders are “segmented” because theyare not defined by continuously smooth surfaces, therefore allowing airto circulate to or from the side of fins 28. In other words, ridges 24and troughs 26 form axially extending circumferentially spaced segmentsof the cylinders. The ridges 24 may also include apertures 29 to allowair contained inside the fins 28 to escape in those instances where theend edge 30 of the fins 28 are in direct contact with the heat producingelectronic device 38, or in those instances where additional air escapepaths are desired to meet the required cooling requirements of thesystem.

[0016] Heat sink assembly 10 also includes a cylindrical heat conductiverod 40 disposed within inner-segmented cylinder 34 defined by troughs 26of heat exchanging section 22. It can be seen in FIG. 2 that the rod hasa greater diameter than inner-segmented cylinder 34. When the rod isinserted into the cylinder within the inside of heat exchanging section22, the folded sheet of the section expands in an accordion-likefashion, whereby troughs 34 are biased into engagement with the outercylindrical surface of rod 40. In other words, the folded sheet whichforms heat exchanging section 22 sort of grips the rod to provide goodheat conductivity therebetween. The rod may be a solid structure, ahollow structure or may comprise a fluid filled heat pipe.Alternatively, the diameter of the rod 40 may be the same as thediameter of the inner-segmented cylinder 34, with the inner-segmentedcylinder 34 being affixed to the rod with any known means of affixingtwo items together, such as an epoxy material or a clamping device (notshown). In the preferred embodiment, the rod 40 is in direct contactwith the heat generating electronic device 38.

[0017] A spring bracket, generally designated 42 (FIGS. 2 and 3), may beused to mount the heat sink assembly 10 to the electronic device to becooled. The spring bracket 42 includes a center ring portion 44 and apair of diametrically disposed arms 46 terminating in apertured latchhooks 48. Ring portion 44 snaps into a circular peripheral groove 50about the rod spaced from the bottom of rod 40. Apertured latch hooks 48at the distal ends of arms 40 snap over a pair of hooked latch bosses 52on opposite sides of base assembly 20. Spring bracket 42 is effective tobias a bottom end 40 a of rod 40 into thermal engagement with heatgenerating electronic device 38. The spring bracket also is effective tospace end edges 30 at the bottom end of folded sheet 22 above the baseplate 41 so that fan assembly 12 circulates cooling air completelythrough fins 28.

[0018] A fan mounting bracket, generally designated 54 (FIG. 2), alsoincludes a ring portion 56 which is appropriately fixed to the top endof rod 40. Four arms 58 radiate outwardly from ring portion 56 andterminate in four mounting posts 60. Appropriate fasteners (not shown)are inserted through four holes 62 in fan assembly 12 and into mountingposts 60 to hold the fan assembly onto bracket 54 which, in turn, ismounted to the top of rod 40.

[0019] Heat generated from the electronic device 38, such asmicroprocessors, semiconductors and the like, within base assembly 20 isconducted to the rod 40 and into heat exchanging section 22 where fins28 dissipate the heat to the atmosphere. Fan assembly 12 causes coolerair from the atmosphere to flow between and around the fins in a heatexchanging fashion.

[0020] Heat sink assembly 10 may also include a thermally conductivebase plate 41 (FIG. 3) which transfers heat to be dissipated to the rod,with the thermally conductive base plate 41 being mounted at the bottomend 40 a of rod 40, and end edges 30 of fins 28 at the bottom end ofheat exchanging section 22 are located above the base plate 41. Thebottom end 40 a of rod 40 may be directly attached to the thermallyconductive base plate 41, such as by welding, brazing or epoxy, or therod 40 and base plate 41 may comprise a single integral structure.

[0021] It will be understood that the invention may be embodied in otherspecific forms without departing from the spirit or centralcharacteristics thereof. The present examples and embodiments,therefore, are to be considered in all respects as illustrative and notrestrictive, and the invention is not to be limited to the details givenherein.

What is claimed is:
 1. A heat sink assembly, comprising: a heatexchanging section including a thermally conductive sheet folded intoalternating ridges and troughs defining spaced fins having opposite endedges, said folded sheet being formed into a generally cylindricalconfiguration whereby the troughs form an inner segmented cylinder andthe ridges form an outer segmented cylinder generally concentric withthe inner cylinder; and a heat conductive rod within saidinner-segmented cylinder defined by said troughs, wherein said rod issolid.
 2. The heat sink assembly of claim 1 wherein said fins aregenerally parallel to each other.
 3. The heat sink assembly of claim 1wherein said fins are generally parallel to said rod.
 4. The heat sinkassembly of claim 1, including a fan mounted on the heat exchangingsection at an end thereof.
 5. The heat sink assembly of claim 1 whereinat least one of the troughs contains an aperture.
 6. The heat sinkassembly of claim 5 wherein the aperture is proximate a bottom end ofthe trough.
 7. The heat sink assembly of claim 1, including a thermallyconductive base plate above which the heat exchanging section ismounted, with the first end edges of the fins of the cylindricallyconfigured folded sheet being between the base plate and the second endedges of the fins.
 8. The heat sink assembly of claim 7 wherein one endof said rod is in engagement with the thermally conductive base plate.9. The heat sink assembly of claim 7 wherein the rod and the thermallyconductive base plate constitute a single, integral structure.
 10. Theheat sink assembly of claim 7 wherein at least one of the troughscontains an aperture.
 11. The heat sink assembly of claim 7, including afan mounted on the heat exchanging section at an end thereof oppositethe thermally conductive base plate.
 12. A heat sink assembly,comprising: a heat exchanging section including a thermally conductivesheet folded into alternating ridges and troughs defining spaced finshaving opposite end edges, said folded sheet being formed into agenerally cylindrical configuration whereby the troughs form an innersegmented cylinder and the ridges form an outer segmented cylindergenerally concentric with the inner cylinder; and a heat conductive rodwithin said inner segmented cylinder defined by said troughs, whereinsaid rod is a heat pipe containing a fluid inside.
 13. The heat sinkassembly of claim 12, including a thermally conductive base plate abovewhich the heat exchanging section is mounted, with the first end edgesof the fins of the cylindrically configured folded sheet being betweenthe base plate and the second end edges of the fins.
 14. The heat sinkassembly of claim 13 wherein one end of said rod is in engagement withthe thermally conductive base plate.
 15. The heat sink assembly of claim13 wherein the rod and the thermally conductive base plate constitute asingle, integral structure.
 16. The heat sink assembly of claim 13,including a fan mounted on the heat exchanging section at an end thereofopposite the thermally conductive base plate.